What is Jabber?
Jabber is the original open instant messaging (IM) technology, invented by Jeremie Miller in 1998 and formalized as the Extensible Messaging and Presence Protocol (XMPP) by the IETF as an Internet Standard for IM and presence.

We use support for In-Band Registration, in-Band Registration is not advertised as a stream feature, protected with CAPTCHA (redirection URL), the minimum informational entropy for passwords = 32 Bit and the frequency of registration from a given IP or username = 1/20minutes. The Web registration limit CAPTCHA calls for JID/IP to 5/minute.

How do I use my jabber account? You can use your jabber account with any of the dozens of free IM clients that support the XMPP standard. See how here.